Broaching machine for gears



ril 8, 1941.

W. L. HANSEN ETAL BROACHING MACHINE FOR GEARS Original Filed March 15, 1937 3 Sheets-Sheet 1 was 47 I v '53 WALL/4M mlillmlllllllllml 11v VEN TORS L lM/VSEN,

A TTORNE Y5 pr 1941' w. L. HANSEN ET AL 2.237.959

BROACHING MACHINE FOR GEARS Original Filed March 15, 1937 3 Shee ts-Sheet 2 ATTORNEYyS' April 8, 1941. w. L. HANSEN ET AL 2.237959 BROACHING MACHINE FOR GEARS I Original Filed March 15, 1937 3 Sheets-Sheet 3 l l lll l l l l l lll l lllllllullllllulml A TTORNE YS.

tion, the thickness of the stock has no influence upon the accuracy of the process.

Hitherto, gears have been cut a single tooth at a time, or by stamping the entire ar with its teeth at a single blow of a press. The production of gears at a single blow will not produce a sufficiently accurate gear wheel for fine clocks, or instruments, and this process also cannot be used for punching thick wheels of small pitch. Ordinarily, it is impractical to punch any hole or tooth in a piece of material smaller than the thickness of the material. Varying thicknesses of the stock, by such prior processes, cause the punch or mounting mandrel to bend sufficiently to make it impossible to cut all of the gear wheels accurately and perfectly.

Referring to the drawings in detail, Figure 1 shows a preferred embodiment of this invention, and consists of a platen l having a fluted punch II with a neck portion |2 inserted in an aperture l3 of the platen Ill. The punch H is provided with peripheral and central aligning pins l4 and I5, respectively. Arranged beneath the plunger II and coaxial therewith is the multiple die, generally designated l6, and consisting of die members ll, l8, l9 and 20. The flutes on the punch extend behind and thereby provide support for the gear tooth portions durin the formation thereof.

These die members are provided with coaxial apertures 2|, 22, 23 and 24, and peripheral apertures 25, 26, 21 and 28, adapted to receive the cap screws 29 which hold the multiple die member within the recess 30 of the die support 3|.

Certain of the upper apertures 25 formed in the 1 upper die member I! are threaded to receive the upper ends of the cap screws 29. The lower die member 20 is provided with a slightly enlarged extension 32 of its forming aperture 24, through which the finished gear passes. 'The finished gear drops through an aperture 33 in the support 3|, and thence into a suitable container or 001- lecting means. Arranged between the aperture 33 and the lowermost die member 20 is an aperture enlargement 34, with which the apertures 35, 36 and 31 communicate. In each set of apertures 35,, 36 and 31 the individual apertures are arranged coaxially (Figures 1 and 2).

The die apertures 2|, 22, 23 and 24 of the multiple die [6 are so configured as to form the gear teeth in successive steps, better shown by a consideration of Figures 3 to 9, inclusive. Figure 3 shows a strip of material 38 having apertures 39, from which gear blanks 40 have been punched and replaced therein, after punching. The blanks 40 are provided with marginal and central recesses or apertures 4| and 42, respectively, for the reception of the aligning pins l4 and I of the plunger Optionally, the blanks 49 may be provided with precut corrugations 43 on the peripheries thereof, as better shown in Figure 5. The latter indicates by the dashed line 44 the exact contour of the finished gear teeth, in contrast with the preliminary corrugated portions 43. If desired, however, a circular die may be used for this pre-cutting operation, thereby providing a blank 40 with a smooth periphery.

The material for making the gears by this process and arrangement may be of any desired nature, such as metal or synthetic resin, the invention having been successfully carried out with both of these materials.

The successive die members l1, l8, l9 and are provided with corrugations 45, 46, 41 and 48 on the walls of the apertures 2|, 22, 23 and 24,

and corresponding to the number of teeth to be formed on the gear wheel blank 40. These corrugations are formed, however, so that each corrugation takes only a small portion of material out of the contour of the tooth. Accordingly, the apertures 2| to 24, inclusive, and their corrugations 45 to 48, inclusive, are arranged to take off from .001 to .005 inch, thereby producing a gear tooth which in every way equals a slowly cut gear tooth formed by a milling or similar operation. The gear wheels formed by the present invention, however, are produced with a single stroke of the punch press, or at the most, with two strokes, one for the blanking operation and the other long stroke for the forming by means of the multiple die.

The material may be of any desired thickness, and is unaffected by the size of the aperture, in contrast with prior art arrangements. For example, it is possible to produce excellent gear wheels with teeth only .019 or .020 inch in width, from stock which is .040 inch in thickness. The present arrangement, moreover, has been found to be the only suitable way by which accurately formed synthetic resin gear teeth can be produced, where these gear teeth are to have perfectly formed tips which are absolutely unbroken. Accordingly, with this process and arrangement, any thickness of material may be used for producing a gear wheel with any pitch of tooth.

In operation the blank 40, either with or without the preliminary peripheral corrugations 43, is placed in the arrangement shown in Figure with its aligning apertures 4| and 42 in engagement with the aligning pins l4 and I5 of the plunger The press is then operated to cause the platen |0 to descend, thereby forcing the blank 40 successively through the forming apertures 2| to 24, inclusive, of the die members H to 20, inclusive.

As the blank 40 passes through the first die member H, the tips of the gear teeth 49 are formed as far as the point 50 (Figure 6), the remainder of the corrugated portions 43 being left untouched. This preliminary formation of each tooth 49 is brought about by the corrugations 45 of the forming aperture 2|. As the lank 40 passes through the corrugations 46 of the forming aperture 22,, in the second die'member 28, the tips of the gear teeth 49 are given a further partial formation, this time as far as the point 5| (Figure 7). Only small portions of the corrugations 43 now remain untouched. As the blank passes through the corrugations 41 of the aperture 23, in the third die member I9, these die corrugations form still further portions of the gear teeth 49, thereby giving the appearance shown in Figure 8. Finally, when the blank 40 is impelled through the final corrugations 48 of the aperture 24 in the last die member 20, the bases of the teeth 49 are formed in such a manner as to complete the gear teeth and present the appearance shown in Figure 9.

Thus, by a succession of steps performed at a single operation, the teeth of the gear wheels are formed. In this manner very little strain is placed upon an individual gear tooth, so there is practically no tendency for the blank to bend or the gear tooth to be forced into a deflected position from which it may be deviated later when the pressure is removed. There is no tendency, also, for the thickness of the material to affect adversely the production of the apertures or teeth because each tooth is formed, not at a single step but by a succession of steps in different dies. Each die is thereby subjected to but a slight strain, in contrast with the great strain placed upon a die used in the production of a gear wheel at a single stroke.

Accordingly, therefore, the machine of this invention permits a blank to be forced through a series of forming apertures, each aperture forming a portion only of each gear tooth so that the gear tooth is produced by a plurality of cuts or forming engagements rather than by a single cut. as in the prior art. The fact that all partial cuts upon the blank are made substantially simultaneously entirely around the periphery of the blank, results in an even pressure being applied to the blank, so that there is no tendency for an eccentric gear to be produced as where a gear wheel is produced by cutting a single tooth at a time. In order to facilitate the alignment of the several parts of the die, dowel rods 52 are provided (Figure 2) at spaced positions around H the periphery thereof.

The space 34 thus forms an annular chamber from which a passageway 53 leads outwardly to a source of pressure fluid, either gaseous or liquid, 7

by which the shavings or cuttings can be expelled and the dies cleared regularly by way of the apertures 35, 36 and 31.- This improves the qual-- ity of the product by preventing any damage to the gears by the action of chips or shavings already in the die. Where the press employed is actuated by pressure fluid for punching out the gear wheels, the exhaust fluid therefrom may be directed through the passageway 53 to expel the cuttings and clear the die.

In the modified construction shown in Figure 10, the multiple die support 3i is mounted upon the platen or ram 54 of the press, whereas the punch II is mounted in a bore 55 in the press bed 56. By this arrangement it is possible to cut an individual blank of a size which is not practical to push back into the strip. In this 'modiflcation, the punch does not move into the die members or portions, as in Figures 1 to 9, but the die members move down over the punch. After the gear wheel has been punched out by these multiple dies, it is pushed through the aperture '32 at the top, and may be removed therefrom either mechanically or by being blown out by compressed air. As before, the blank may be properly located by the use of the pins l4 and 15 mounted on the punch. In this modification, however, the punch is stationary and the die members or portions are movable by being attached to the platen or ram. Furthermore, by the use of the locating pins I4 and I5 itis possible to make larger gears than it is possible to part only of each gear tooth portion by a given die member, and a punch having plural aligning members adapted by mere engagement thereof with guide holes in the gear wheel blank to guide the tooth portions of the gear wheel blank in rectilinear paths during the formation thereof, means for spacing the working surfaces of at least two of said dies from each other to form a circular space between said dies, a closed passageway communicating with said space at one end of said passageway and having means at its other end for connection to a source. for removal of the die cuttings.

2. A machine for producing gear wheels comprising a series of apertured die members having corrugated walls of differing characteristics, the walls of the earlier die members in the series being adapted to form one part only of each gear tooth and the walls of the later die members being adapted to form a different part only of each gear tooth, and a punch having projections arranged to extend behind the gear tooth portions whereby to provide support for said gear tooth portions during the formation thereof, means for source for removal of the die cuttings.

3. A machine for producing gear wheels comprising a series of spaced apertured die members having forming elements associated therewith, the forming elements of the earlier die members of the series being arranged to form the tip parts only of each gear tooth and the later forming elements being arranged to form the base parts only of each gear tooth, and a punch having projections arranged to extend behind the gear tooth portions whereby to provide support for said gear tooth portions during the formation thereof,

1 means for spacing the working surfaces of at least two of said dies from each other to form a circular space between said dies, 9. closed passageway'communicating with said space at one end of said passageway and having means at its other end for connection to a source for removal of the die cuttings, one of said die members having a the forming elements of the earlier die members of the series being arranged to'form the tip parts only of each gear tooth and the later forming elements being arranged to form the base parts only of each gear tooth, and a punch having projections arranged to extend behind the gear tooth portions whereby to provide support for said gear 1. A machine for producing'gear wheels comprising a plurality of die members with corrugated apertures arranged in succession, the apertures being successively configured to remove a tooth portions during the formation thereof. means for spacing the working surfaces of at least two of said dies from each other to form a circular space between said dies, a closed passageway including longitudinal apertures through said dies communicating with said space at one end of said passageway and having means at its other end for connection to a source for removal of the die cuttings.

WILLIAM L. HANSEN. IRA. N. BURST. 

